This proposal deals with the development of light microscopic neuroanatomical techniques which can ultimately be integrated into neurophysiological and ultrastructural studies of afferent central nervous system connections from the Oro-facial area. The proposed experiments will utilize Horseradish peroxidase histochemistry as a dental research tool. Recent work in this laboratory has shown that this enzyme has been picked up by sensory receptors of the Oro-facial area and carried via retrograde axonal transport to the trigeminal complex in the brain stem. Studies are described which should make this method: 1) applicable to the morphological analysis of sensory nerve endings of the dental pulp and the temoromandibular joint and the localizations of their terminals, 2) useable in determining the rate and distribution of protein, 3) applicable for the identification of specificity of central organization in terms of modalties of sensory input, and 4) applicable to the analysis of sensory nerve endings of any Oro-facial area and the localization of their terminals.